Advanced television systems sometimes include a load detection mechanism to detect an external electrical load of a digital-to-analog converter. The digital-to-analog converter can be included in, for example, a graphics card of a computer and can operate to supply a video signal to be displayed by a television set. Detection of the external electrical load indicates that the digital-to-analog converter is connected to the television set. During operation of an existing load detection mechanism, a predetermined electric current is supplied at an output end of the digital-to-analog converter, and a voltage at the output end of the digital-to-analog converter is detected. As can be appreciated, the voltage at the output end of the digital-to-analog converter depends on an effective electrical load of the digital-to-analog converter, which, in turn, depends on whether the external electrical load is connected to the output end of the digital-to-analog converter. If a certain threshold voltage is exceeded, the external electrical load is deemed to be disconnected. On the other hand, if the threshold voltage is not exceeded, the external electrical load is deemed to be connected to the output end of the digital-to-analog converter.
An existing load detection mechanism can operate in a satisfactory manner for certain types of television sets having direct current (“DC”)-coupling at their inputs. However, television set manufacturers have expressed interest in using AC-coupling at inputs of television sets, such as by including coupling capacitors that are connected to input ports of the television sets. Such AC-coupling can defeat operation of an existing load detection mechanism. In particular, since a coupling capacitor can behave as an “open-circuit” under certain conditions, an external electrical load may be deemed to be disconnected even if the external electrical load is actually connected to an output end of a digital-to-analog converter.
It is against this background that a need arose to develop the apparatus, system, and method described herein.